The invention relates to a down-hole assembly, such as a tubing plug, and to the particular structure for holding the assembly in place in a tubing hanger or the like and a method associated therewith. While the present invention is desirably utilized with a tubing plug, the principles thereof may also be utilized with a packer, plug, retainer, or other similar down-hole structures. The term "tubing hanger or the like" means tubing hangers, well casings, etc.
According to the structure of the present invention, several simple components are provided which effect the holding of the plug or the like in a down-hole position and allow ready removal thereof. The down-hole assembly includes a cylindrical cage, a tubular mandrel disposed concentrically within the cage, a spline connection between the cage and the mandrel being provided, a sleeve camming means concentric with the cage and mandrel and disposed therebetween, and holding means radially movable with respect to the cage for holding the down-hole assembly in place. Locking means are provided for locking the camming means into place, and means are provided operatively connected to the camming and locking means for receiving an actuator member (i.e. polish rod) for actuation of the camming and locking means. Upon axial movement of the sleeve, camming portions thereof cam the holding means outward into engagement with the tubing hanger and may simultaneously compress sealing means so that they move radially into sealing engagement between the cage and the tubing hanger. The sleeve is then locked in place by the locking means, a rotative mode of operation of the locking means resulting in the locking of the sleeve in position. When release of the holding means is desired, release may be effected by reverse rotation of the locking means, or by removal of a retaining nut acting between the locking nut and the mandrel. Quick release of the holding means may thus be effected.
A locating ring may also be provided for facilitating holding of the assembly in proper position within a tubing hanger upon linear axial movement of a camming means so that the whole structure is not displaced during camming of the holding means into holding position. The friction between the tubing hanger, holding means, camming means, and cage means upon axial movement of the camming means may be minimized by the provision of spring means acting between the cage means and the locating ring.
When a tubing plug is provided as a down-hole member, the plug may include a tubular valve housing attached to the mandrel at the lower end thereof, a check valve being disposed within the valve housing and biased into sealing engagement therewith. The check valve may include a spring biased dart shaped valve member having a spring biased pilot valve disposed therein.
According to the method of the present invention, a down-hole member is located in place by lowering the down-hole member into a tubing hanger with a running tool to the desired down-hole position. A structure for holding the down-hole member in place in the tubing hanger is then actuated by actuation of the running tool in a first mode, and the structure for holding the down-hole member in place is locked in the holding position by actuation of the running tool in a second mode different from the first mode. The first mode is preferably a linear axial movement, whereas the second mode is a rotative movement. Removal of the running tool from the well casing may be effected only after locking of the holding structure for the down-hole member in place.
Also according to the method of the present invention, the down-hole member may be removed in one of two ways. The first way comprises the steps of actuation of the running tool in said second mode to release locking of the holding structure, actuating the running tool in the first mode to deactivate the holding structure, and removing the down-hole member from the tubing hanger by raising the running tool, detachment of the running tool and down-hole member being prevented. According to the second manner of removal of the down-hole member, another tool is actuated in a third mode to simultaneously release locking of the holding structure and release holding of the holding structure, and subsequently the down-hole member is removed with the running tool. The third mode of operation can include unscrewing a locking screw holding a retaining nut in engagement with the mandrel and the locknut.
It will be seen that according to the present invention a structure has been provided which provides simple yet secure locking of a down-hole member in place in a tubing hanger. Removal of the running tool for locking the member in place is not possible until the lock has been completely effected. Both the holding and locking of the down-hole member are accomplished by movement of the same running tool. In an emergency situation, the down-hole member can be released by removal of a retaining nut rather than by movement of a locking member. Simultaneous actuation of the holding member and sealing members can be effected, and the whole structure is held in place during the movement of the holding members into place by a locating ring. It will be seen that the structure according to the present invention is simple yet effective for accomplishing its desired function.
It will additionally be seen that also according to the present invention a method has been provided for locking a down-hole member in place and for removing the down-hole member, the locking of the member in place and the removal of the member both being accomplished by simple actuation of a running tool, and the locking taking place in a failsafe manner. Emergency release of the down-hole member is also provided for.
It is the primary object of the present invention to provide a simple method and apparatus for effectively securing a down-hole member in place in a well casing. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.